Hammer mill



Jan. 19, K WHITE ET AL HAMMER MILL Filed March 2, 1940 2 Sheets-Sheet l Jan. 19, 1 H. K. WHITE ETAL HAMMER MILL Filed March 2, 1940 2 Sheets-Sheet 2 00000 O O O OO 00000000002 0 O O O nl u l 121 EIZZUFE Haroflf K, White George Stephen Patented Jan. 19,1943

HAMDIEBMILL Harold K. White and George A. Stephen, Chicago, lll.-, assignors to Weber Bros. Metal Works, Chicago, 11]., a corporation of Illinois Application March 2, 1940, Serial No. 321,810

6 Claims.

This invention relates to ahammer type pulver'izing mill and more specifically relates to a portable p'ulverizing mill readily adapted for laboratory use.

While the invention will be hereinafter specifically described in connection with a small, portabledaboratory pulver'izing mill, it should be understood that the invention is not limited to portable units, or to size, and that the construction of the parts may be widely varied without departing from the scope of the invention.

The portable pulverizing mill of this invention includesa base plate and clamp assembly for quick -mounting of the unit on a table, laboratory bench' or the like support. A high speed electric motor is fixedly mounted on the base plate for driving a drive shaft extending into a housing which is vertically mounted on the front end of the base plate and adapted to overhang the front edge of the table or work bench on which the unit is mounted. The housing itself is a die forging or casting having an annular side wall, an integral centrally apertured rear wall accommodating passage of the drive shaft therethrough, and a depending hollow chute adapted to receive a collecting bag around the lower end thereof.

A plurality of bolts are swivelly mounted at spaced intervals around the periphery of the housing for securing a removable front face plate on the housing to close the front end thereof. The face plate itself has an inlet passageway formed thereon for supplying material to the interior of the housing.

A feature of the invention includes a removable annular lining member'for the side wall of the housing. This liner can be replaced when worn and fully protects the housing forging or casting. A screen of segmental cylindrical shape is disposed over the bottom portion of the side wall of the housing above the hollow chute to retain material in thehousing until it has been pulverized to a size sufficiently small for passing through the screen. The screen is readily replaceable with other similarly shaped screens of different mesh.

A rotor is mounted on the drive shaft in the housing and carries a plurality of hammers around the periphery thereof.v A feature of the invention includes the free mounting of the rotor on the drive shaft and the uniting of the rotor to the drive shaft by means of a loose key which is fixed in position by a ball bearing and-manually operated wedge. This construction facilitates removal of the rotor from the drive shaft.

The electric motor is connected with the drive shaft through a flexible coupling and is adapted to rotate the shaft at very high speeds of the order of 10,000 revolutions per minute.

The compactness, simplicity, high capacity and efflciency of'the laboratory units of this invention contribute to correct a great deficiency in the prior art.

It is, then, an object of the invention to provide a compact reducing mill which .is readily adapted to be mounted on a table or laboratory bench.

Another object of the invention is to provide a small, high-capacity, portable hammer mill.

A further object of the invention is to provide a hammer-type portable mill for laboratory use.

A specific object of the invention is to provide a hammer-type mill with replaceable liners and screens. l

A still further specific object of the invention is to provide a hammer mill housing with a removable face that is adapted for quick mounting on the housing to close the same.

A further specific object'of the invention is to provide a rugged bearing assembly for a portable hammer-type mill to smoothly support a high speed drive shaft.

Another specific object of the invention is to provide a simplified rotor construction for a hammermill including a disc member with a grooved Other and further objects of the invention will become apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings, which disclose a preferred embodiment of the invention.

On the drawings:

Figure 1 is an isometric view of a portable hammer mill according to this invention with a portion of the cover broken away and shown in vertical cross section.

Figure 2 is a fragmentary vertical cross-sectional view of the hammer mill shown in Figure 1.

Figure 3 is a vertical cross-sectional view taken along the line III-III of Figure 2.

Figure 4 is a cross-sectional view taken along the line IV--IV of Figure 3.

Figure 5 is an isometric view of a liner ring for the hammer mill housing.

Figure 6 is an isometric view of a screen unit used in the hammer mill.

Figure '1 is an enlarged vertical cross-sectional view, with parts shown in elevation, taken alon the line VII-VII of Figure 3.

Figure 8 is a fragmentary plan view taken along the line VIII-VIII of Figure '7.

' As shown on the drawings:

In Figures 1 to 4 the reference numeral Ill designates generally the cast metal housing of the mill. The housing l includes an open face cylindrical side wall ll having apertures Ila along the bottom half thereof (Figure 3) and an integral back wall l2. The cylindrical side wall ll merges into a hollow depending outlet l3. The outlet l3 surrounds the apertures Ila in the bottom half of the side wall. The outlet l3 thus defines a chute for passage of pulverized or reduced material from the interior of the housing defined by the cylindrical side wall II and back wall l2 to a bag l4 disposed around the open bottom end thereof. The bag l4 preferably has an elastic top I4a for contracting the mouth of the bag to hold the bag on the chute l3.

Ribs I! are formed at spaced intervals around the side wall II and along the back wall l2 to I increase the bursting strength of the housing.

Pairs of lugs ii are formed at spaced intervals around the cylindrical side wall II at the open front thereof. Pivot pins l1 are secured at their ends in the ears Ii and each pin bridges the space between a pair of pins to pivotally support an eye bolt l3 having a threaded shank I8a receiving a wing nut l9 thereon.

As shown in Figures 1 and 2, a flat horizontal plate 20 is formed integrally on the back of the housing I0 intermediate the top and bottom of the housing. The plate 20 has a second plate 2| extending from the rear edge thereof and welded or otherwise secured thereto along a half-lap joint portion 22 thereof. The plates 20 and 2| form a platform or supporting base 23 adapted to be set on a table or laboratory work bench. Obviously the platform 23 could be formed in one piece by an extension of the plate 20 but is illustrated as being formed from two plates to render the casting less complicated.

A boss 24 (Figure 1) projects horizontally from the rear wall of the chute portion l3 and is cast integrally with the chute or welded thereon. A turnbolt 25 is threaded through the boss 24 and has a disc 26 rotatably mounted on its top end. The turnbolt 25 can be rotated to carry the disc 23 against a laboratory work bench or table for fixedly mounting the base 23 on the bench or table.

As best shown in Figure 2, the back wall l2 of the housing has an annular recessed portion l2a receiving the flanged end 210 of a tubular bearing housing 21. Bolts 28 extend through the flange 21a and hold the bearing housing 21 in fixed assembled relation on the back wall of the housins ID.

A drive shaft 29 extends through the tubular housing 21 and has an enlarged end 230. extending into the housing in through an aperture l2b formed in the back wall l2 thereof. The enlarged end 230 has running clearance with the back wall l2 around the aperture l2b. A recess 21b is formed in the front end of the bearing housing 21 and receives a felt retainer washer 30 therein. The retainer washer 30 is snugly disposed around the enlarged portion 23a of the drive shaft and is held in the recess 21b by means of a metal retainer disc 3|. A pair of ball bearing assemblies is mounted in the housing 21 adjacent the opposite ends thereof and each ball bearing assembly includes an outer race ring 32 snugly seated in the housing 21, an inner race ring 33 snugly disposed around the shaft 23 and ball bearings 34 between the race rings.

A spacer tube 35 is slidably mounted in the tubular housing 21 between the outer race rings 32 of the bearing assembly. A second spacer tube 36 is slidably mounted on the shaft 23 between the inner race rings 33. i

A locking ring 31 is threaded into the open rear end of the tubular housing 21 against the outer race ring of the rear bearing assembly to cooperate with the tube 35 to hold both outer race rings in flxed spaced relation in the housing 21. Likewise, a locking nut 33 is threaded around the shaft 23 for thrusting against the inner race ring of the rear-bearing assembly to cooperate with the spacer tube 36 for holding both inner race rings in proper spaced relation.

The shaft 23 has an integral reduced portion 23b projecting from the rear end of the housing 21 and receiving one side of a flexible coupling 39 thereon. A leather disc 40 or other flexible means joins the two parts of the coupling 33 together.

The rear portion of the coupling 33 is secured to the armature shaft 4| of an electric motor 42 '(Figure ll A switch 43 is mounted on the rear end of the motor 42 and a cord and plug assembly 44 is connected to the switch for plugging into a source of electric current.

A U-shaped cover 45 preferably has the legs thereof mounted along the sides of the base 23. The cover 45 extends over the top of the electric motor 43 and around the coupling 33 and bearing housing 21. The side walls of the cover 48 may be perforated if desired to permit a draft of air to flow into apertures 42a on the motor 42. An armature cooling fan can be provided in the motor if desired.

A lubricant supply tube 46 extends from the shaft bearing of the electric motor 42 through the top of the cover 45. Likewise, a grease tube 41 extends from the bearing housing 21 through the top of the cover and receives a grease cup 48 on the upper end thereof for supplying the bearings in the housing 21 with lubricant.

The enlarged portion 29a of the drive shaft 29, as best shown in Figures 2, 3 and 7, has a key slot 230 extending inwardly from the end of the shaft. A rotor 50 is mounted in the housing III on the enlarged end 23a of the drive shaft. This rotor can be in the form of a solid metal disc apertured at the center to receive the drive shaft and having three annular grooves 50a, 53b and Bio around the periphery thereof. The central aperture in the rotor has a key slot 53d therethrough.

A key Si is loosely seated in the slots 28c and 500 to hold the rotor against relative rotation on the shaft.

As best shown in Figure 7, the enlarged portion 29a of the shaft has a transverse well 23d therein opening into the slot 230. The. end of the enlarged portion 29a of the drive shaft is tapped for receiving a set screw 52 in threaded engagement therewith. This set screw has a tapered end 520 adapted to project into the bottom of the well 29d. A ball bearing 53 is seated in the well and when the set screw 52 is threaded into the drive shaft so that the tapered end 52a thereof enters the bottom of the well, the ball is urged outwardly against the key SI for locking the key hammers.

in the slots 28c and 500. A loosening of the set screw 52 will permit the ball to drop to the bottom of the well so that the key and rotor can be readily removed from the drive shaft. This arrangement facilitates removal of the rotor from the drive shaft since if a tapered key were used in wedging' engagement with the rotor and drive shaft it might be so firmly afllxed in the slot that a wheel puller would be necessary to remove the rotor from the shaft. However, the loose fit of the key in the slot insures an easy removal of the rotor whenever the ball is released by the set screw.

As shown in Figure 3, the end of the set screw has a polygonal aperture 52b for'receiving an operating tool.

Striking bars or hammers 54 are mounted at their inner ends in the grooves 50a, 50b and 500 of the rotor. Pivot pins such as bolts 55 extend transversely through the grooves and through the hammers 54 to pivotally carry the hammers.

As best shown in Figure 8, two bars 54 are mounted on a single pin 55 in the outer grooves 50a and 50c while a single bar is mounted on .each next adjacent pin 55 in the middle groove 50b. This provides-a staggered arrangement of The hammers are free to swing back and forth relative to the rotor 50 and, as shown in.Figures 2 and 3, project into spaced relation from the housing.

When the leading edges of the hammers become worn, the rotor can be readily reversed on the drive shaft so that the opposite edges of the bars will become leading edges.

As shown in Figures 2, 3 and 4, the interior of the cylindrical side wall H of the housing Iii is lined with an annular liner 55 extending across the full width of the housing around the upper half thereof but only having a narrow portion 56a extending around the bottom half of the housing adjacent the rear wall thereof. The liner member 56 is secured in the housing by means of retaining screws I51. As best shown in Figure 5, the unit 58 is a ring member with a wide top half and a narrow bottom half. The bottom half portion 5611, as pointed out above, is disposed adjacent the rear wall of the housing. The liner 56 has tab portions 56b depending from the lower end of the wide top half portion thereof. These tabs 56b and the narrow portion 55a are of reduced thickness so that they are spaced inwardly from the housing walls.

A screen unit 51 is removably mounted in the lower half of the cylindrical portion ll of the housing to cover the openings Ila. This screen unit 51 has a segmental cylindrical shape and includes a rigidifying strip 51a welded to the inner face thereof along its outer edge. The strip 51a, as shown at 58 in Figure 4, may be stamped with indicia designating the size of the screen. Thus, as shown at 58,- the strip 51a is stamped to indicate that the screen is a 50-mesh screen.

As also shown in Figure 4, the screen 51 is adapted to be disposed under the ring portion 560 of the liner 56 and in back of the tab 55b of the liner. The screen is thus held in position between the side wall ll of the housing and the liner member. As shown in dotted lines in Figure 4, the screen projects behind the wide top half portion of the liner but the rigidifying strip 5;; terminates adjacent the lower end of the tab 5 This mounting provides for a ready replacehammers.

'or face plate 80 having peripheral notched re--'- cesses 6| adapted to receive the shanks l8a of the eye bolts I8. The wing nuts l9 are then tightened against the outer face of the cover 60' to hold the same in fixed position for closing the housing. The cover is preferably formed with spaced radial ribs '62 to increase the strength thereof.

As shown in Figure 2, the cover 50 is centrally apertured as at 63 and this aperture is covered with an inlet tube 64 secured to the outer face of the cover by means of screws or bolts 65. The inlet tube 54 is inclined upwardly and has a bowlshaped mouth 55 at the top end thereof. The bowl 58 is disposed above the top of the housing II and communicates at the bottom thereof with the tube 64 thru a reduced throat 56a that prevents clogging of the tube.

Material to be pulverized or reduced is merely dumped into the bowl 66 and flows by gravity through the tube 64 and through the aperture 53 into the housing l0 where it is acted upon worn, the rotor can be readily reversed so that the normally trailing ends of the hammers become leading ends.

It will be noted from Figure 2 that the rotor sets on the drive shaft for a length that is greater than the space between the rotor and the cover so that in the event the locking key becomes dislodged, the rotor cannot fly off of the drive shaft.

From the above description it should be understood that this invention provides a compact, portable hammer mill readily adapted for laboratoy usage. The mill has high capacity and includes replaceable liners and screens as well as A set of different sized screens can be furnished with the mill for controlling the amount of reduction in particle size to be obtained by the mill. Thus the material is always retained in the milling chamber until it is sumciently reduced to pass through a screen of selected size. The rugged bearing assembly for the rotor and the flexible coupling between the prime mover and rotor provide a smoothly operating unit.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims. i

We claim as our invention:

1. A liner and screen assembly for a hammer mill comprising a one-piece cylindrical collar having a wide top portion and a narrow bottom portion of reduced thickness connecting the ends of the wide portion, and a sieve shaped as a segment of a cylinder and adapted to project around and behind said narrow portion.

2. A liner and screen assembly for a hammer ment of screens since the unitcan be quickly slid mill comprising a cylindrical collar having a wide top portion and a narrow bottom portion connecting the ends of the wide portion, a pair oi tabs projecting from the ends of the wide portion in spaced relation from the narrow portion, a sieve shaped as a segment of a cylinder adapted to project around said narrow portion and behind said tabs and a reinforcing strip secured to the inner face of said screen extending between the tabs.

3. A liner ring for a reducing mill comprising an annular sleeve, a portion of said sleeve being substantially of the same axial width as the portion of the mill it lines, the balance oi. said sleeve being a narrow band of reduced thickness connecting the ends of said wide portion, said portion and said band of the sleeve having outer edges and inner surfaces in flush relation, and a tab of generally the same width and thickness as said narrow band depending from each end of said wide portion in the same relation as said narrow band but spaced therefrom.

4. A true cylindrical liner and screen assembly comprising a cylindrical collar having a Wide top portion and a narrow bottom portion, said narrow bottom portion being of reduced thickness and having one surface thereof flush with an adjacent surface of said wide top portion and its other and opposite surface spaced in a radial direction relative to the collar from the other and adjacent surface of the wide top portion to provide a circumferential recess in the collar, and a sieve shaped as a segment of a cylinder and arranged to be seated in said circumferential recess on said narrow bottom portion in flush relation with said other surface of the wide top portion.

,5. In a hammer mill, a housing defining a cylindrical chamber and a radially extending discharge chute opening into' the bottom of the chamber, a removable cylindrical liner within said chamber having a wide portion seated against a side portion of said housing and a connecting narrow bottom portion adjacent an edge of the opening to the chute, and a removable sieve for mounting in said chamber to seat on said housing over the chute opening therein under the narrow liner portion to extend between the ends of said wide portion on the l er.

6. A hammer mill comprising a castinr having a hollow chute portion and a cup-shaped portion whose axes are angularly disposed to each other, the back wall of said cup-shaped portion having an opening therethrough and a recess in one face thereof concentric with said opening, a base on said casting integral therewith at the junction between said chute and cup-shaped portions and extending rearwardly from said back wall, a detachable cover plate and feed inlet for the open end of said cup-shaped portion, a screen between said cover plate and said back wall and overlying said hollow chute, a clamping device on said chute portion spaced from said base which together coact to hold said hammer mill on a support, a rotatable drive shaft extending through the aperture in said back wall and terminating short of said cover plate, and a bearing assembly for said drive shaft carried by the back wall of the cup-shaped portion having one end seated in the recess in said back wall.

HAROLD K. WHITE, GEORGE A. STEPHEN. 

